The research team led by Director JO Moon-Ho of the Center for Van der Waals Quantum Solids at the Institute for Basic Science (IBS) has implemented a new method for achieving epitaxial growth of 1D metallic materials with a width of less than 1 nm. The group applied this process to develop a new structure for 2D semiconductor logic circuits. Specifically, they used 1D metals as the bram electrode of an ultra-miniaturized transistor.

Integrated devices based on two-dimensional (2D) semiconductors, which exhibit excellent properties even at the ultimate thickness limit down to the atomic level, are a major focus of basic and applied research worldwide. However, the realization of such ultra-miniaturized transistor devices that can control electron movement within a few nanometers, let alone the development of a manufacturing process for these integrated circuits, faces significant technical challenges.

The degree of integration in semiconductor devices is determined by the width and control performance of the bram electrode, which controls the flow of electrons in the transistor. In conventional semiconductor manufacturing processes, reducing the bram length below a few nanometers is impossible due to lithography resolution limitations. To solve this technical problem, the research team utilized the fact that the mirror twin boundary (MTB) of molybdenum disulfide (MoS₂), a 2D semiconductor, is a 1D metal with a width of only 0.4 nm. They used this as the bram electrode to overcome the limitations of the lithographic process.

In this study, the 1D MTB metallic phase was achieved by controlling the crystal structure of the existing 2D semiconductor at the atomic level, transforming it into 1D MTB. This represents a significant breakthrough not only for next-generation semiconductor technology but also for fundamental materials science, as it demonstrates the synthesis of new material phases through artificial control of crystal structures.

The International Roadmap for Devices and Systems (IRDS) by IEEE predicts that semiconductor node technology will reach around 0.5 nm by 2037, with transistor bram lengths of 12 nm. The research team demonstrated that the channel width modulated by an electric field applied from the 1D MTB bram can be less than 3.9 nm, which significantly exceeds futuristic predictions.

The 1D MTB-based transistor developed by the research team also offers advantages in circuit performance. Technologies like FinFET or Gate-All-Around, used for miniaturizing silicon semiconductor devices, suffer from parasitic capacitance due to their complex device structures, leading to instability in highly integrated circuits. In contrast, the 1D MTB-based transistor can minimize parasitic capacitance due to its simple structure and extremely narrow bram width.

Director JO Moon-Ho commented: "The 1D metal phase achieved by epitaxial growth is a new material process that can be applied to ultra-miniaturized semiconductor processes. It is expected to become a key technology for the development of various low-energy, high-performance electronic devices in the future."

This research was published on July 3 in the journal Nature Nanotechnology.

Source: Institute for Basic Science, Korea